If you love Magit and haven't thought about donating before, I think it's something worth considering. Knowing in advance how good it is, and how much easier it makes your life, consider... if Magit didn't exist at all, but you could pay some money to make it suddenly exist in its current form, would you do that? How much is it worth to you?

You can apply the same thought experiment to any free software project you love, of course. If you're in the fortunate position of having some disposable income, and you've never donated to a free software developer before, consider doing it -- not only will they feel extra-appreciated for their amazing efforts, but it might inspire them to make even more improvements to the software you love.